{"id":"5ccea987-c1d6-593f-a564-4d363b6e1892","stable_key":"f992b796-377d-53bf-a39b-7e5d41dbe194:b5-bio-ppcs-atp-preference","predicate":"preferentially_uses","statement":"Under the reported coupled-assay conditions, human PPCS activated substrate with ATP about four times more efficiently than with CTP.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"26b33051-f2eb-5152-b213-abf3b7597d1c","mechanism_event_label":"Human PPCS favors ATP; bacterial nucleotide preferences should not be substituted for the human result.","subject":{"id":"0a912ac0-8179-5884-9cf7-e8a0053e4d21","slug":"ppcs","display_name":"Phosphopantothenoylcysteine synthetase / PPCS","entity_type_key":"protein"},"object":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"26b33051-f2eb-5152-b213-abf3b7597d1c","stable_key":"f992b796-377d-53bf-a39b-7e5d41dbe194:b5-bio-ppcs-atp-preference-event","event_type":"biochemical_relationship","label":"Human PPCS favors ATP; bacterial nucleotide preferences should not be substituted for the human result.","description":"Under the reported coupled-assay conditions, human PPCS activated substrate with ATP about four times more efficiently than with CTP.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"7b039e4f-7fa6-5d8e-ac1d-2c115f49fc13","slug":"phosphopantothenate","display_name":"4-Phosphopantothenate","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"ca899f13-50ad-55e5-ab99-329ae0038c74","slug":"l-cysteine","display_name":"L-Cysteine","entity_type_key":"small_molecule"},"role":"cosubstrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"0a912ac0-8179-5884-9cf7-e8a0053e4d21","slug":"ppcs","display_name":"Phosphopantothenoylcysteine synthetase / PPCS","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"1 mM ATP versus 1 mM CTP, with 1.5 mM phosphopantothenate and 5 mM cysteine; 37°C.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Reported relative assay efficiency, not a universal kinetic constant; the paper contrasts the stronger CTP preference of E. coli PPCS.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"pantothenate","display_name":"Pantothenate (vitamin B5)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Human PPCS favors ATP; bacterial nucleotide preferences should not be substituted for the human result.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified recombinant protein; no intact tissue","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"7e995513-ab6b-5a68-bec9-1abe61e0a45b","evidence_kind":"source_excerpt","locator":"Lines 535-546","start_line":535,"end_line":546,"excerpt":"### b5-bio-ppcs-atp-preference\nUnder the reported coupled-assay conditions, human PPCS activated substrate with ATP about four times more efficiently than with CTP.\nCondition category: normal\nnutrient_topic: Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Human PPCS favors ATP; bacterial nucleotide preferences should not be substituted for the human result.\norganism: Homo sapiens\ntissue_or_cell_type: Purified recombinant protein; no intact tissue\nexperimental_model: Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution\nlimitations: Reported relative assay efficiency, not a universal kinetic constant; the paper contrasts the stronger CTP preference of E. coli PPCS.\nexposure: 1 mM ATP versus 1 mM CTP, with 1.5 mM phosphopantothenate and 5 mM cysteine; 37°C.\ncross_nutrient: false\n[b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200","model_system":"Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"0716b500-dd0b-5425-b9d0-d88bc9c09e86","stable_key":"import-f992b796-377d-53bf-a39b-7e5d41dbe194","title":"Pantothenic acid (vitamin B5): coenzyme A, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"b5a49f5a2373ca6064c9a4e014e052dad2f6f199a82bb09b26b82b831c36110b","revision_id":"78f3e793-f084-5ee2-8703-b661c4b650bf","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}